Patent GB-711234-A (GB)
Title: Improvements in and relating to ejection seats for aircraft
IPC: B64D25/10
Filed: 1951-09-07
Abstract: 711,234. Ejector seats for aircraft and parachute release mechanism. MARTIN, J., and MARTINBAKER AIRCRAFT CO., Ltd. Aug. 19, 1952 [Sept. 7, 1951; April 24, 1952], Nos. 21135/51 and 10325/52. Class 4 An ejection seat for aircraft having a frame on which the seat is mounted, an ejection gun operating between the seat frame and a fixed part of the aircraft to eject the seat and its frame, a main or personal parachute, a drogue gun, a drogue parachute, seat safety harness, face screen and means to release the drogue parachute from the seat; the seat harness, and the face screen, the drogue parachute withdrawing the main or personal parachute, said release means being normally locked but unlocked for actuation by a timing mechanism, is characterized by the combination of a drogue shackle normally retained in a scissors shackle or slip members fixed to the seat, a parachute pack container, an apron or sling in the latter and on which the parachute pack normally rests, and lifting lines, connected to the drogue shackle so that when this is freed from the member by release mechanism, the face screen is released, the apron is straightened out to eject the pack from the container, the pack is opened up and the main or personal parachute withdrawn, and means also operative on the freeing of the drogue shackle to release the seat safety harness. When the face screen 48, Fig. 1, is pulled down it fires the ejection cartridge (not shown) and the resulting upward movement of the seat disengages a gear 15, Fig. 5 which withdraws a latch 14 to free a spring loaded rack 10 in mesh with a restraining clockwork mechanism 12. Downward movement of the rack 10 permits rocking movement of a bell-crank 9 which frees a spring loaded plunger 6 and thus frees a cross tube 7 locking the scissors shackle securing the drogue line 4 to the seat. The time delay mechanism incorporates a barostatic device comprising a bellows which holds a pin in engagement with a wheel 22 above a pre-determined altitude. The lower end of the plunger 6 caries a pin 25, Fig. 5, which moves downwardly with the plunger to release a latch mechanism, Fig. 7 (not shown), and free a spring loaded barrel 29 to which a cable 31 is secured to operate the releasing lever of the pilot's safety harness box 30, thus freeing the pilot from the seat. The drogue, now free of the seat, pulls a bi-furcated extension 34, 35, 36 of the cable 4 to withdraw quick release pins 39 and free the face screen 48 and to release other fastenings 45 that secure a head pad 38 and an apron 40 in position adjacent the seat back. The apron 40, in straightening out, ejects the parachute pack 51 from its container 49 and becomes finally released from the seat by separation of a pair of lower fastenings 50. The cables 35, 36 pass behind and through the apron 40 and terminate in a cable 43 which, as a final operation, releases the closures of the parachute pack and withdraws the pilot's parachute. For this purpose the pack 51 has two release pins 55 normally engaging closures 56 and the rip cord 57, Fig. 12, is connected to one pin 55 by a loop 58 and to the other pin by a line 62. The cable 43 extending through the apron 40 ends in a loop 44 which is secured to a sleeve 63 on the end of the cable and passes through a further loop 61 on the end of a cable 60 attached to the parachute canopy. Another sleeve 66, free to slide on the sleeve 63, carries a pin 65 that engages the loop 44 and this latter sleeve is releasably connected to a manual - control cable 70. In automatic operation the cable 43 withdraws the pins 55 by means of the connections 61, 62 and then, by the cable 60, withdraws the parachute from the pack 51. In manual operation, the pilot first draws on cable 70 to withdraw the pin 65 in order to separate the loops 44 and 61 and release the parachute pack from the cable 43 attached to the seat, and then operates the rip cord 57 to free the pins 55 and withdraw the parachute. Specifications 583,257, 640,520, 652,131 and 673,147 are referred to.